Are successful princes faithful?

Machiavelli, as might be expected, focuses on the fox as a metaphor on how to act: “a prudent prince cannot and should not keep his word when to do so would go against his interest.” To be crafty and to be able to deceive, the mythical hallmarks of the fox, are key skills for any ruler. You can break promises and treaties as long as you can hide your duplicity; you must therefore be “a great liar and hypocrite.” So, no successful Princes are not necessarily "faithful".